We have an exciting meeting planned for this month. David Agnew of Gates Air will be presenting a new way of sending our STL signals to our transmitter site.

Transporting Robust and Secure FM Composite Multiplex Signals in an IP based STL

Dave Agnew

GatesAir Mason, Ohio

Abstract – The emergence of high bandwidth IP network connections is an enabler for the transport of the FM composite multiplex (MPX) signal in a Studio-to-Transmitter Link (STL). When architecting a STL network topology, transporting an MPX signal vs baseband FM components has advantages in terms centralized distribution and control. Two methods of MPX interconnection are digital and analog. Methods of transporting IP based MPX signals include RF, private and public IP based services. All present tradeoffs in terms of required bandwidth, signal quality, security and compatibility. Digital MPX over AES offers the possibility of an all-digital processing chain, while analog MPX can offer greater flexibility and compatibility with legacy equipment. New IP based MPX STL’s now offer both analog, digital MPX and the ability to carry HD Radio™ E2X data. We review the need for bridging and interoperability between newer digital FM exciters and legacy analog FM exciters. We also review various MPX STL topologies, examine where various elements can be located, networking requirements, IP based STL tools for reliable and secure MPX signal transport over the most commonly used IP connections. Use cases are presented to illustrate differences between all analog, all digital, and dual domain FM MPX STLs and the tradeoffs they present with respect to compatibility and network bandwidth, scalability, and delay. Discussion and real world examples of MPX over IP reliability and security tools used are presented here as well.

We are fortunate to be able to get great speakers with the help of Bob Eburg and Art Reed from Bradley Broadcast Sales in Frederick.

Meeting will be held on September 20th, 12:30 pm in the penthouse at WBAL, 3800 Hooper Avenue in Baltimore. Since we are back in the city, we will be ordering from cafehon.com. Go to the website and make your choice of food and email it to me. Gates Air will be buying lunch.